1. Field of the Invention
The present invention relates to a large diameter, high power zoom lens.
2. Description of the Related Art
Conventionally, a large number of variable focus lenses aimed at achieving high zoom ratios have been proposed. Such variable focus lenses, for example, include sequentially from an object side at least a positive first lens group, a negative lens group, a positive third lens group, a positive fourth lens group, and a positive fifth lens group, and focuses an image of an object by moving the fifth lens group (refer to Japanese Patent Application Laid-Open Publication Nos. 2005-345714 and 2001-75008).
The zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2005-345714 includes at least 5 lens groups that are positive, negative, positive, positive, and positive respectively from the object side, has an angle of view exceeding 62° at the wide angle edge, and realizes a zoom ratio of 11.3 or greater. Further, the zoom lens recited in Japanese Patent Application Laid-Open Publication No. 2001-75008 includes at least 6 lens groups that are positive, negative, positive, positive, negative, and positive respectively from the object side, has an angle of view exceeding 42° at the wide angle edge, and realizes a zoom ratio of 11.1 or greater.
Although the zoom lenses recited respectively in Japanese Patent Application Laid-Open Publication Nos. 2005-345714 and 2001-75008 realize high zoom ratios of 11 or greater, the F number also significantly increases accompanying zoom and thus, enlarged images become dark. Furthermore, the angle of view is insufficient.